# `Ulid`

A sortable unique identifier: 26 capital letters and digits.

Use it when you receive ids in this form. For your own records, [`Uuid`](/docs/types/type-uuid.md) is what Jadpo generates.

## Shape

One value, held as text in one set form, with no parts: `7ZZZZZZZZZZZZZZZZZZZZZZZZZ`.

## Example

```jadpo
Ulid("01ARZ3NDEKTSV4RRFFQ69G5FAV")
```

`Ulid(raw)` checks the text, and text that isn't one breaks the `format` rule.

`text.parse(raw, as: Ulid)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `8ZZZZZZZZZZZZZZZZZZZZZZZZZ`, `01arz3ndektsv4rrffq69g5fav` or `01ARZ3NDEKTSV4RRFFQ69G5FAI`.

## Good to know

- It is upper case. The first character can't be above `7`.
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it.

## In JSON

A string, in a request, a response or `json.write`:

```json
"01ARZ3NDEKTSV4RRFFQ69G5FAV"
"7ZZZZZZZZZZZZZZZZZZZZZZZZZ"
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`Ulid` is in the group Software, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `01ARZ3NDEKTSV4RRFFQ69G5FAV` and `7ZZZZZZZZZZZZZZZZZZZZZZZZZ`.

### How it is stored

It is stored in one column named for the field, of type `text`. `7ZZZZZZZZZZZZZZZZZZZZZZZZZ` is stored as `'7ZZZZZZZZZZZZZZZZZZZZZZZZZ'`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `01ARZ3NDEKTSV4RRFFQ69G5FAV` | `01ARZ3NDEKTSV4RRFFQ69G5FAV` |
| `7ZZZZZZZZZZZZZZZZZZZZZZZZZ` | `7ZZZZZZZZZZZZZZZZZZZZZZZZZ` |

### Operations

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>